Side wing blade assemblies are extensively urged on snowplow vehicles. A typical side wing blade arrangement comprises an elongated curved blade and an articulated attachment system for mounting the blade to the snowplow. More specifically, the mounting system comprises a spring loaded coupling for connecting the front end of the blade to the vehicle, and an articulated hanger unit for connecting the rear end of the blade to the snowplow chassis and also for tilting the wing between a plowing position and a retracted position. In the plowing position, the blade extends at an angle to the longitudinal axis of the vehicle engaging the road surface, while in the retracted position it is lifted up and extends generally parallel and close to the vehicle cabin.
Initially, commercially available side wing blade assemblies were equipped with a cable and sheave system to tilt the blade. This system was progressively abandoned in favour of various types of hydraulically operated devices, due to complexity and high maintenance costs. As a result, the reliability and the performance of side wing blade assemblies have been substantially improved. Still, there is much room for improvement in two other major areas which are those of blade stability during the plowing operation and of blade deflection, the latter phenomenon allowing the blade to yield when it encounters an obstacle. Blade deflection is extremely important when the side wing blade assembly is designed for a lighter truck where the inertial mass of the vehicle is substantially reduced and in absence of adequate blade yielding capability, the vehicle may be seriously damaged when the blade hits an obstacle. It should be appreciated that an unrestricted blade deflection is not desirable either, since the blade may be violently thrown against the vehicle as a result of a strong impact against an obstacle, which may thereby cause substantial body damage.